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THE JOINT INFLUENCE OF SUCCAROSE AND HIGHLY DISPERSED CALCIUM HYDROSILICATES ON THE STRENGTH DEVELOPMENT KINETICS OF CEMENT CONCRETE

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 83-94 p.
Abstract
Сement hydration accelerator (highly dispersed calcium hydrosilicates) and hydration retarder (sucrose) are components of calcium silicate dispersion (CSD). Their joint influence on the processes of setting and hardening of cement composites is considered. The content of 10% CSD in the composition of the composite binder (CB) leads to a shift of the thermal maximum on the thermokinetic curve by a day. At the same time, at the late stages of hydration (>70 hours), the heat release rate remains consistently high, it is 2-3 times higher than the heat release rate of the control sample. The setting kinetics of CB pastes depends on the content of CSD in its composition and is of an extreme nature. The effectiveness of CSD in the composition of CB was evaluated on the example of ordinary heavy concrete (B25) with the replacement of cement with CSD. The results of assessing the change in the strength of concrete at CB are supplemented with calculated strength indicators in the future up to 1800 days hardening. The expected compressive strength of concrete samples on a composite binder is 1.8 times higher than the strength of the control sample.
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STUDY OF THE EFFECT OF ANIONS ON THE DISSOLUTION RATE OF CO2O3 AND CR(OH)3

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 95-100 p.
Abstract
Сhromium compounds are widely used in industry, therefore, studies related to the study of the process of dissolution of oxides in various environments, including aggressive ones, are relevant. Currently, a huge amount of experimental material has been accumulated on the dissolution of metal oxides and hydroxides. Despite this, the effect of anions on the dissolution rate of these compounds has not yet been sufficiently studied, models have not been developed and generalized dissolution mechanisms have not been found. This article presents experimental studies on the effect of nitrate and sulfate ions on the dissolution rate of chromium (III) oxide and hydroxide. It was found that chromium (III) oxide and hydroxide dissolve better in sulfuric acid in the presence of nitrate ions than sulfate ions. Moreover, chromium (III) hydroxide dissolves better in acids with the addition of anions than chromium (III) oxide. Based on the data obtained, using the equation of the chain mechanism (the Barton-Stransky model), we found the functional dependence of the specific rate of dissolution on the concentration of anions in an acidic medium. With the help of the mathematical computer program MathCad, models of the dissolution of chromium oxide phases were selected. A scheme of the mechanism of the heterogeneous process of dissolution of chromium oxide and hydroxide in acidic media was proposed.
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PURIFICATION OF OIL-CONTAINING WASTE WATER FROM HERMETIA ILLUCENS FLY LARVAE LIPID CONCENTRATE PRODUCTION

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 5-16 p.
Abstract
The work is devoted to the study of the possibility of waste water from the lipid concentrate (oil) obtained on the basis of the larvae of the Black Soldier fly (Hermetia Illucens) production treatment. Treatment of oily wastewater is not an easy task due to the specific properties and condition of the oils contained in such wastewater. Typically, wastewater containing fats and oils has a high chemical oxygen demand (COD), biological oxygen demand (BOD), large amounts of suspended solids, oils, fats, phosphates and sulfates. Various physicochemical methods are used to treat such wastewater. However, the search for inexpensive effective materials for the oils extraction from aqueous media is an actual task.
For cleaning, we used the crushed fruits of the Sycamore tree – a deciduous tree widespread in the southern strip of the Russian Federation. Model emulsions containing "Black Soldier" larvae oil were subjected to cleaning. The influence on the purification efficiency of such factors as the dose of the sycamore fruit (SF) added biomass, the SF interaction duration with the emulsion, and the pH of the medium was investigated. It was found that high purification efficiency is achieved at the SF dose of 1 g per 10 cm3; pH = 4; the duration of the contact is at least 10 minutes.
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INVESTIGATION OF PHOTOPROTECTIVE PROPERTIES OF TROXERUTIN, FERULIC ACID, AQUEOUS EXTRACTS OF LEMON BALM (MELISSA OFFICINALIS), AND PEPPERMINT (MENTHA PIPERITA) BY UV SPECTROSCOPY

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 17-28 p.
Abstract
Both natural and ingredients created in laboratories are used as photoprotective agents in cosmetic products. This paper presents the results of a study of photoprotective properties of aqueous extracts of lemon balm (Melissa officinalis) and peppermint (Mentha piperita), aqueous solutions of troxerutin and ferulic acid by UV spectroscopy. The work objective was to evaluate photoprotective qualities of these substances, for which such indicators calculated from UV spectra as sun protection factor – SPFin vitro, the critical wavelength – λcrit and the ratio of the areas under the absorption spectrum curve in the ranges 320-400 nm and 290-320 nm – UV-A/UV-B. The stability of the studied objects to the action of UV radiation was also checked. During the work carried out, it was found that the aqueous extracts of lemon balm and peppermint have particular photoprotective properties. At the same time, the extract obtained from lemon balm and purified from ballast substances showed the highest value of SPFin vitro. However, with prolonged UV irradiation simulating sunlight, the absorption properties of plant extracts decrease. Troxerutin absorbs UV rays mainly in the wavelength range of 320-400 nm, is resistant in aqueous solutions to UV radiation, air oxygen, and can be used as a UV-B filter in cosmetic compositions. Ferulic acid absorbs UV radiation mainly in the wavelength range of 280-320 nm, but under the influence of ultraviolet, the absorption properties of this substance change significantly. A change in the nature of the UV spectrum of ferulic acid is also observed under the influence of air oxygen.
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ESTIMATION OF UNCERTAINTY OF GRADING SAMPLES FOR X-RAY FLUORESCENT DETERMINATION OF RHENIUM CONTENT

 29-38 p.
Abstract
For the development and metrological certification of the procedure for measuring the mass fractions of rhenium in metallurgical samples by the extraction-X-ray fluorescence method, solid-phase samples-emitters were prepared to construct a calibration characteristic. The article evaluates the values of the expanded uncertainty of the emitter samples using the Bayesian approach. The sources of uncertainties associated with the preparation of the standard solution, the preparation of the extractant, the extraction process and the measurement of the analytical signal intensity were identified: the error of a volumetric flask and a pipette; the error in measuring the time and temperature of extraction, the error in the expansion of the volume of the flask at the stage of preparation of solutions, the error in the scales when measuring the mass of the extractant and when measuring the weight of the weighed portion of ammonium perrhenate, the error in measuring the optical density on an X-ray fluorescence spectrometer for the prepared emitter samples, repeatability of the results when measuring the analytical signal - emitters, linearity of the calibration characteristics. A quantitative assessment of each source of uncertainty was made, the contribution to the value of expanded uncertainty of all stages of the process was estimated. It was found that the greatest contribution to the value of the total uncertainty is made by the error associated with the error at the stage of preparation of the extractant and the stage of extraction concentration and extraction of the analyte from the liquid phase to the solid. An equation for calculating the total standard uncertainty is derived. The results obtained can be used in the metrological substantiation of the procedure for performing measurements of the ex-traction-X-ray fluorescence determination of the rhenium content in metallurgical samples.
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INFLUENCE OF PROBIOTICS IN THE COMPOSITION OF FEED SUBSTRATE ON THE AMINO ACID PROFILE OF HERMETIA ILLUCENS LARVES

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 39-47 p.
Abstract
The use of probiotics Bacillus subtilis B-8130 and Bacillus licheniformis B-4162 as part of the feed mixture in the cultivation of larvae of the black soldier fly Hermetia illucens influenced the features of the amino acid profile of the larvae. The greatest impact was caused by B. licheniformis B-4162, which caused a statistically significant decrease in the level of 10 of the 18 essential amino acids, including the sulfur-containing amino acids cystine and methionine. B subtilis B-8130 demonstrated an unreliable tendency to decrease the total amino acid content, but statistically significantly reduced the cystine content compared to the control.
The revealed changes in the amino acid content in the larvae occurred against the background of an increase in their mass compared to the control larva. It is assumed that the decrease in the level of amino acids is associated with their expenditure on the formation of glucose and metabolic energy in a more intensively developing larva on a feed mixture with a probiotic.
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NICKEL IONS ADSORPTION BY THERMOMODIFIED FALLEN LEAVES OF CHESTNUT

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 48-59 p.
Abstract
In recent years, the attention of researchers has been attracted by industrial and agricultural waste, which can be used as sorption materials. A special group is made up of lignocellulose-containing components of woody biomass (leaves, bark, needles, fruits, etc.) and wood processing products (sawdust, shavings, chips, etc.). Advantages of using the latter as reagents for wastewater treatment include simple technique, small processing, good adsorption capacity, selective adsorption of heavy metal ions, low cost, free availability and easy regeneration. Trees foliage attracts attention аmong the components of the woody biomass, it has a large specific surface area and falls annually under the conditions of the Russian Federation, which facilitates its collection and use.
Nickel ions are one of the most toxic pollutants that enter water bodies with industrial wastewater. The infor-mation on the nickel compounds toxic effect on living organisms is briefly presented. In this work, we studied the sorption properties of chestnut fallen leaves (CFL) in relation to nickel ions. The sorption capacity maximum value of the thermally modified CFL at a temperature of 250° C (CFL250) is 1.3 mmol / g for nickel ions. By processing the obtained isotherm within the framework of the Langmuir, Freundlich, BET, Dubinin-Radushkevich sorption models, it was found that the adsorption process is most accurately described by the Langmuir model (R2 = 0.9912). The calculated Gibbs energy is equal to -7.86 kJ / mol, it indicates the occurrence of spontaneous physical adsorption of Ni2 + ions on the CFL250 surface.
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NANOPERFORATION TECHNOLOGY AND FUNCTIONAL PROPERTIES OF COPPER STRUCTURED MATERIALS IN THE PROCESS OF GLUCOSE ANODIC OXIDATION

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 60-69 p.
Abstract
The paper presents an original technology for the synthesis of nanostructured copper electrodes by the method of replicas from metallic aluminum nanomatrices on a pilot high-voltage galvanic installation. The technological scheme used makes it possible to carry out the process of continuous high-voltage microplasma perforation of a metal tape with the formation of nanopores of a given size in the range from 20 to 500 nm at a variable voltage. To study the received replicas, a series of indicator electrodes with a working surface made of replica material was created. Cold rolled copper foil was used as a reference material for the electrode. The visible area of the working surface of the manufactured electrodes was examined using a scanning electron microscope. By the method of cyclic voltammetry, the coefficient of increase in the specific surface area was determined by increasing the peak area corresponding to the reduction of the surface film of copper oxide formed on the surface of the copper electrode in an alkaline medium at positive potentials. For a smooth copper electrode, the surface area was 0.071 mm2. For a nanostructured electrode of the same size, the total surface area was calculated with respect to the ar-eas of current peaks corresponding to the reduction of the surface film of copper (II) oxide on the surface of a mas-sive copper electrode and a nano-porous copper electrode. It was found that the catalytic activity, estimated by the magnitude of the current associated with the oxidation of the model substrate – glucose, is approximately 10 times higher than the increase in activity due to the total surface of copper. The anomalous catalytic effect is discussed from the point of view of increasing the local electric field strength due to the high curvature of the surface of nan-ofibers and from the point of view of changing the conditions of diffusion of the substrate to the electrode surface due to nanostructuring.
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APPLICATION OF ELECTRODIALYSIS FOR PRODUCTION OF MAGNESIUM HYDROXIDE FROM SEA WATER

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 70-83 p.
Abstract
Magnesium hydroxide is an important component of many technological processes, it has found wide application in food, polymer, light industry, while synthetic magnesium hydroxide has a number of advantages over natural, namely, it has a higher decomposition onset temperature, there are no unwanted impurities in the structure product, it has a higher degree of whiteness, as well as the ability to change the specific surface area (activity) and dispersion of particles during synthesis during synthesis. The way of obtaining magnesium hydroxide by membrane methods can be called the most modern and modernized today, membrane technology is attractive for developers and investors: the processes of separation of liquid media proceed at temperatures close to the ambient tem-perature, their flow is controlled and predictable. At the same time, with regard to the production of electrolytes in modern chemical technology, electromembrane processes, in particular, electrodialysis, are widely used. It is pro-posed to use sea water as a raw material - a natural resource with a changing chemical and bacteriological com-position depending on the depth of sampling, temperature, and natural conditions. The technological scheme of production is represented by the main stage (two-stage fractional precipitation in a batch apparatus with a stirrer) and auxiliary equipment (ultrafiltration unit, bipolar electrodialysis unit, reverse osmosis unit, etc.); developed to separate magnesium hydroxide from seawater while simultaneously solving the problem of the implementation of intermediate products, which ensures care for the environment. The developed production of chemical reagents, in particular, magnesium hydroxide, implements the processes of fractional precipitation and electrodialysis. The re-sults of calculating the economic efficiency of the method indicate the quick payback of the project, the low cost of a kilogram of the target product.
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EXTRACTIVE DISTILLATION OF TERNARY MIXTURES WITH TWO BINARY AZEOTROPES

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 84-92 p.
Abstract
The phase equilibrium of the n-butanol – n-butyl acetate – methyl isobutyl ketone system was studied using a computational experiment. To separate the mixture, an extractive distillation in the presence of various solvents: dimethyl sulfoxide, N-methyl-2-pyrrolidone and sulfolane was selected. The calculation of the vapor-liquid equilibrium of derivatives of quaternary systems (original ternary system + separating agent) was carried out and the difference in the change in the relative volatility of azeotrope-forming pairs of components in the presence of different solvents was shown. Two separation flowsheets with different structures were proposed. The columns operation parameters that ensure the production of substances of marketable quality with minimal energy consumption were determined. It was shown that the lowest energy consumption is observed for a flowsheet with dimethyl sulfoxide as the most selective agent.
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